1. Field of the Invention
This invention is concerned with the utilization of waste dust and waste sludge from blast furnaces and steel works. More particularly, the invention is concerned with the utilization of the aforementioned waste materials without the disadvantageous sulphuration.
2. Description of the Prior Art
It is well known that the problem of dumping the dust and sludge produced in waste gas purification in iron and steel works is worldwide. As the dumping and the disposal of these materials is not viable on either ecological or economical grounds, many attempts have been made to make use of the waste materials. Thus, it was proposed, firstly to form the waste materials into pellets containing basic gangue and having higher sulphur contents at a metallization degree of 80% and to use these pellets in the melting of steel in blast furnaces, see, for example, German Offenlegungsschrift 2,519,810 and "Stahl und Eisen" 1976, Vol. 24, Pages 1228-1233.
In addition to the preferred use of the pellets in blast furnaces, attempt was also made to use the metallized pellets with sulphur contents of approximately 1% as the cooling means in the refining process in LD converters. 10-50 kg of pellets per ton of steel was added. The test melts showed that the sulphur charged with the pellets was absorbed up to 50% by the steel. Therefore, the use of pellets as cooling means is only limited.
The process for producing the pellets is itself part of the prior art (Stahl und Eisen, 1976, Vol. 24, Pages 1228-1233).